Centbiitjgax casting machine



Aug. 26, 1930. 1. A, GARDNER ET AL Re. 17,783

CENTRIFUGAL CASTING `lvumxrmm Original Filed March 4, 1927 glow/rif irre/wref Reiua Aug. ze, 1930 UNITED STATES Re.V 17,783:

PATE/Nr OFFICE# "-CENTRIFUGAL GASTING MACHINE original no. 1,694,5o4, dated reissue :nea June 21, 1930. seriaiJNo. 462,920.y

In the casting of very small articles of gold or other similar and particularly highly 'refractory metals, such'for instance as metal inlays for dental Work, jewelry, etc., difficulty is experienced in transferring the metal from the crucible to the mold Iquickly enough and with suiiicient force to cause the metal to flow into the delicate parts. These difficulties have been artially solved by what are known as centrifugal casting machines, in which the mold is placed on a rotatable arm and a crucible located on the same arm, between the mold and the center of rotation, and in which 'afterl the metal in the crucible has been sufficiently heated, the arm is caused to rotate rapldly and the metal to thereby be thrown into the mold centrifugally. In these machines however, many incidental pointsv are as` yet unsolved or only crudely solved and it is to these points that our invention is largely directed.

Among these points are, first, that while the finer parts of the casting are taken care of by the centrifugal action, the amount of rotation securable by the spring action ordinarily used, is insulicient to provide a duration of rotation which will permit the larger parts of the casting to solidify before it ceases, and therefore releases have been interposed which vpermit the arm to rotate after the spring aetion is spent.

Second, the crucible and mold is ordinarily heated and the -metal melted before'these parts are placed on the arm, andameans for effecting quick and positive attachment of the Crucible and mold must be provided; and

Third, the motion imparted to the arm being sudden and powerful, provision should be made for positioning the Crucible and mold so that the initial tagential motion may be 40 utilized, but these parts'being the heavier parts and at the end of the arm, provision should be made for accomplishin?, rigidity after they have taken up a radial position in order to etlectually utilize their inertia and keep the arm in balance.

The objects of this invention are, and this invention relates,

(1) To means for reducing the frictional relation between the parts initiating motion '5 and those continuing the rotation after the vto the portion power of the motor has been spent; such object primarily being accomplished by placing the lockingl and-releasing means at the point of ultimate attachment of the arm to the source of power;

(Q) To means secure 'attachement of the Crucible and inold partsto the arm;

v (3) To means for limiting themovement of the mold carrying arm initially to. a tangential position, andthereafter to a radial position; and

(4) Tomeans for improving construction o f such a machine.

The means by which the foregoing and other objects are accomplished, and the man.- ner of their accomplishment, will readily'be understood from the following` specification,

generally, the

-on reference to the accompanying-drawings,

in which,-

Fig. 1 is a sectional side elevation ofthe machine with Crucible and mold in place.

Fig. 2 is a plan view, with the Crucible and mold removed, and

Fig. 3 is/a fragmentary sectional side elevation on the line III-III of'Fig. 1, showing the releasing pawl.

Referring now to the drawings in which the various parts have been indicated by numerals,10 is a casing in which is mounted a vertical shaft 11, supported at its lower end on a ball 12, and provided near its upper' end with a hall bearing assembly 13, the inner portion of which is secured on the shaft and the outer portion in the upper portion of the casing. 14 is a retaining cap securing the bearingin the casing. 15 is a flat coil spring,

manner' to the shaft and-the other to the casing. l

16 is a collar, secured above the bearing 13, 17 of the shaft, by a pin 1S,

assing through the shaft and collar and protion 17 the shaft is reduced in diameter to form a shoulder against which the inner portion of a ball-bearing assembly 19 is forced and secured to the shaft by a nut 20.

December 11, 1928, Serial No. 172,874, led March 4, 1927. .Application for foreecting the quickand jecting laterally therebeyond. Above the sec- 21 is the throwing arm, to which is secured.

in any desired manner, a retaining member I 22 into which the-outer half of the ball-bear-l ing assembl v 19 has been forced. 23 isa hole in the arm t rough which the nut 20 projects. Projecting laterally from 'the member 22 is 5 apin 24 on which a pawl '2 5 is hinged and f depends into the Vpath of the pin 18. This. pawl as 4will be seen by reference to Fig.y3v

swingsupward to permit its passage over the pin in one direction, when the pawl moves to w the right in that view, butv is restrained by the shoulder 26 from swinging in the opposite direction, so that it will engage the pin when the pawl is'moved to the left in winding, or be engaged by the pin when the latter is n;A moved to the right by the spring action.

I Secured to one end of the( throwing arm 21 is a bearing 27, through which passes a pin 28 rigidly securedin one end of an oscillat able extension 29' of the throwing arm, thus ,2g providing for the extension of a pivotal support, vbut one substantially rigid against vertical movement.V 30 is a brace ysecured to theI extension and bracing against lthe lower end of the pin 28 to giveadditional rigidity to 25 that member. 31, 32 are lugs or stops on the arm 21, and 33 is a pin secured in, and de-` pending below, the'L-extension 29 whichpin engages the lug 31 to determine a position of v the arm tangential to the circle of movement `30 of the p in`28, and which pin' likewise engages the-lug 32'to determine a true radial position of the extension.

The end' -34 `of the extension arm 29, is preferably turned upwardly at right angles $5 to the arm to form a stop or abutment. A shield 35 maybe secured thereto and form a part of the stop. 36is a slotin the arm having an enlarged eye37 located at the inner end ofV i 5o radially outward until the endof the mold abuts solidly against the stop 35. The ta- 'pered slot allows at the same time a minor wedging action ofthe pin 40 against the slot sides, but such wedging should not he 55 suliicient to prevent the mold from seating firmly against the stop. Where longer cru-- cible-mold assemblies are used, a largerpin may be used 1n order to get a similar-wedgmg action at a point more remote from the stop.

i It will.` be seen that not fonly is the mold "uickly and firmly en 'ged,but centrifugal e orce ofthe machine w en in -use additionally tends'to make the attachment moresecure.

.42 is a weight adjustably secured to the o 05 end of the. throwingarm, which weiglit may be moved inward or youtward until it balances the weights on the opposite armi-end and thereafter be secured by tightening the -nut 43.

. 44 is apin, vertically slidable in the casing 10, which may be raisedvupward into the Y path of the arm 21 to form a stop therefor,

should same be desired. The casing 10 may be secured to any suitable suppdrt in any de sired manner. A

. In use the weight 42 is adjusted to the proper location to balance the 'particular'crucible and mold to be used'andthese, after the metal has first been melted in suitable apparatus, are en agedwith the slotted arm 29, with the mold rmly seated' against the stop. The arm 21 is then turned in the direction ofthe arrow A in Fig. 2, until the spring 15 is wound p up. During such winding the pin 33 moves the extension arm in thesame direction of rotation and .prevents its swinging in the wrong direction. After winding, the arm 21 is released and the spring allowed to rotate it rapidly in the reverse direction. At the l start of such reverse motion, the mold tends by inertia to lag behind and the extension arm assumes a tangential instead of vradial position. At such time the pinl 33 engaging the lug 31 prevents the varm from swinging too far I inward. After the parts have been set in full radial position, the metalin the-Crucible thus being, at all parts ofthe movement, impelled toward the mold. j

-When'the spring 'has spent its force, the arm continues to revolve, the ball-hearing 19 substantially eliminating friction and the pawl 25, Fig. 3, riding over the pin 18 with a minimum of resistance, so that with the arm mounted `for rotation at the ultimate vpoint of connection with the shaft, friction is practically eliminated and rotation will l motion the extensionl arm again assumes a continue for a very considerable period, thus allowing the etal in the mold to cool and solidify While still under centrifugal pressure. During this period too, the pin 33 engaging the lug 32 prevents the mold end of the arm from over-running the remainder thereofand in maintaining them in alignment, maintains them in balance.

It will of course' he understood that the drawings are illustrative only, and that vav rions modifications may be vmade in the, details of construction without departing from the spirit of our invention. We therefore,

wish it distinctly understood that we do not wish to limit ourselves to the details herein shown and described, except as same may be specifically hereinafter set out in the claims. VHaving thus disclosed our invention, what weclaim is 1.. A casting ap arat'us comprising a vertical shaft, means fbr drivin s aid shaft during a limited period, amo d carrying arm mounted for free rotation on the extreme upper end of said shaft, a pin projecting from said shaft, a pawl carried by said arm, depending into -thepath of said pin during action of said driving means, and over riding said pin when driving action is (spent.

2. Acasting apparatus, comprlsm arotatable arm, an extension arm pivote thereto and means for limiting the swing of said extension arm, comprising oppositely disposed lugs projecting longitudinally from said rotatable arm, and a pin projecting from said extension arm and disposed between said lugs.

tatable arm, an extension arm pivoted there- Y to, and means carried by yone of said arms,

cooperating with the other thereof, for limiting the swing of said extension arm away from alignment with said rotatable arm to determine initial angular positioning of said arm.

4. A casting apparatus, includin a rotatable arm, an extension arm pivote thereto, and a stop carried by one of said arms, cooperating with the othervthereof, for limiting the swing of said extension arm away from alignment with said rotatable arm to determine initial angular positioning of said arm.

5.` A casting apparatus, including a rotatable arm, an extension arm pivoted thereto,

`and a stop carried by one of said arms, co.-

operating with the other thereof, for limiting the swing of said extension arm away from alignment with said rotatable arm to an i initial position substantially at right angles to said rotatable arm.

6. A casting apparatus, including a. rotatable arm, an extension arm pivoted thereto, and means carried by one of said arms cooperating with the other thereof, for limiting the swing of said extension. arm between a position in alignment with said rotatable arm, and an initial position at an angle thereto.

7. A casting appara-tus, including a rotatable arm, an extension arm ivoted thereto, and a stop carried by one o 'said arms, c0- operating with the other thereof, for limiting the swing` of said extension arm between a position in alignment with said rotatable arm and an initial position substantially .at

right angles thereto, y,

In testimony whereof we have hereunto set our names.

JOSEPH A. GARDNER. DAVID S. GARDNER.

3. A casting apparatus, including a ro-A 

